PTGS2 and rheumatoid arthritis: The phenomena that inflammatory cytokines such as IL-1β and TNF-α stimulate matrix degrading enzymes such as matrix metalloproteinases (MMPs) and cyclooxygenase-2 (COX-2), through activation of NF-κB, leading to cartilage matrix destruction, joint inflammation and play an important part in pathogenesis of RA and OA [152].